The aim of our investigation is to examine the roles of neurotransmitters and protein synthesis in memory trace formation. In particular, attention will be devoted to the physiological processes occuring during the "consolidation period" of memory trace formation. The purpose of the research is to examine the processes responsible for the formation of memory traces in the mouse. The guiding hypothesis is that the formation of the long-term memory trace is dependent upon protein synthesis and that it is also influenced by and dependent upon short-term memory. Much of the proposed work will be an extension of the pharmacological analysis of the short-term memory trace in order to elucidate its nature. In general we have found that memory trace formation can be facilitated by centrally acting stimulant drugs and impaired by depressant drugs. Furthermore, in an attempt to localize memory trace formation in the brain we will inject a variety of drugs directly into the brain at a variety of times before and after learning. To examine the generality of our findings at least three different types of learning will be studied: passive avoidance, active avoidance, and maze learning.